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Machaeroprosopus lottorum
Topic Started: Feb 1 2014, 01:44 PM (2,184 Views)
Taipan
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Machaeroprosopus lottorum

Posted Image
An artist's impression of a phytosaur.

Temporal range: Late Triassic, Norian

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Phytosauria
Family: Phytosauridae
Node: †Leptosuchomorpha
Subfamily: †Pseudopalatinae
Genus: †Machaeroprosopus
Species:Machaeroprosopus lottorum

Machaeroprosopus is an extinct genus of pseudopalatine phytosaurid from the Late Triassic of the southwestern United States. M. validus, once thought to be the type species of Machaeroprosopus, was named in 1916 on the basis of three complete skulls from Chinle Formation, Arizona. The skulls have been lost since the 1950s, and a line drawing in the original 1916 description is the only visual record of the specimen. Another species, M. andersoni, was named in 1922 from New Mexico, and the species M. adamanensis, M. gregorii, M. lithodendrorum, M. tenuis, and M. zunii were named in 1930. Most species have been reassigned to the genera Smilosuchus, Rutiodon, Pseudopalatus, or Phytosaurus. Until recently, M. validus was considered to be the only species that has not been reassigned. Thus, Machaeroprosopus was considered to be a nomen dubium or "doubtful name" because of the lack of diagnostic specimens that can support its distinction from other phytosaur genera. However, a taxonomic revision of Machaeroprosopus, conducted by Parker et al. (in press), revealed that UW 3807, the holotype of M. validus, is not the holotype of Machaeroprosopus, while the previously named species Pseudopalatus buceros has priority as the type species of the genus. Therefore, the name Pseudopalatus must be considered a junior synonym of Machaeroprosopus, and all species of the former must be reassigned to the later. This revised taxonomy was already accepted in several studies, including Stocker and Butler (2013). Stocker and Butler (2013) also treated M. andersoni as a valid species, and not a junior synonym of Machaeroprosopus buceros as was previously suggested by Long and Murry (1995).

Posted Image
The skull of the phytosaur Machaeroprosopus lottorum.

M. lottorum
M. lottorum was first described and named by Axel Hungerbühler, Bill Mueller, Sankar Chatterjee and Douglas P. Cunningham in 2013. The specific name honors John Lott and Patricia Lott Kirkpatrick, for their support during the work at the TTU VPL 3870. It is known from two complete skulls, the holotype TTU-P10076 and the paratype TTU-P10077 housed at Texas Tech University. The skulls were collected at Patricia Site (TTU Vertebrate Paleontology Locality 3870), 13 km South of Post, Garza County of west Texas, from the upper unit of the Norian Cooper Canyon Formation, Dockum Group. Other vertebrates known from this site include TTU-P10074, a partial skull referred to Machaeroprosopus sp., a phytosaur postcranial skeleton, fish, a temnospondyl amphibian, Typothorax, Postosuchus, Shuvosaurus and a theropod dinosaur.
A phylogenetic analysis of pseudopalatine phytosaurs performed by Hungerbühler et al. (2013) found the species to be a derived Machaeroprosopus species, most closely related to the type species of Redondasaurus, "R." gregorii. This clade in addition to Machaeroprosopus sp. (TTU-P10074) was recovered as the sister taxon of the clade formed by M. pristinus and M. buceros. M. jablonskiae, M. mccauleyi and "Redondasaurus" bermani were found to be basal species of Machaeroprosopus.




Triassic-age 'swamp monster': Rare female phytosaur skull found in West Texas more than 200 million years old

Date: January 29, 2014
Source: Texas Tech University
Summary:
In the dangerous waters of an ancient oxbow lake created by a flooded and unnamed meandering river, the female phytosaur died and sank to the bottom 205 million years ago. About 40 yards away the remains of a larger male also came to rest, and both disappeared in a tomb of soil and sediment. Evidence for the cause of their deaths and the rest of their bodies have vanished with time, but their skulls remained. After careful research, a paleontologist says he and others have discovered a new species of the Triassic-age monster in the wilds of West Texas.

Posted Image
The female skull still had its teeth intact, which made the find even rarer.

In the dangerous waters of an ancient oxbow lake created by a flooded and unnamed meandering river, the female phytosaur died and sank to the bottom 205 million years ago. About 40 yards away the remains of a larger male also came to rest, and both disappeared in a tomb of soil and sediment.
Evidence for the cause of their deaths and the rest of their bodies have vanished with time, but their skulls remained. After careful research, a Texas Tech paleontologist says he and others have discovered a new species of the Triassic-age monster in the wilds of West Texas.
Their findings were published in the peer-reviewed journal Earth and Environmental Science Transactions of the Royal Society of Edinburgh.
Bill Mueller, assistant curator of Paleontology at the Museum of Texas Tech University, said the team named their find Machaeroprosopus lottorum after the Lott family who own the ranch on which the animal was discovered.
"We found them in an area we'd been excavating in," Mueller said. "I think we've gotten four skulls out of that area already. Doug Cunningham found this specimen, and then we dug it up. When he found it, just the very back end of the skull was sticking out of the ground. The rest was buried. We excavated it and brought it into the museum to finish preparation."
Cunningham, currently a field research assistant at the museum and a retired firefighter, remembered finding the unusual female skull on June 27, 2001. After removing it from the mudstone, he recalls looking it over carefully with others and wondering if his discovery would add a new animal to science.
"It was really well preserved with the teeth and everything," Cunningham said. "Finding one with teeth is pretty rare. It was so odd, but when they come out of the ground, you have a long way to go to actually see what you have because they're still covered in matrix. We were all kind of in awe of it. It had this long, skinny snout. It was quite a bit different. It took me years to get it prepped and ready. At the time, I was working full-time and I did that on my days off." By looking an opening on the skull called the supratemporal fenestra, the snout and the shape of the bones at the back of the head, the team compared it to other phytosaurs and determined they'd discovered a separate species.
While West Texas is dry and dusty today, Mueller said the landscape looked more like a swampy, tropical rainforest during the Triassic period. Our planet's landmasses had converged to form the supercontinent of Pangaea. In the forest undergrowth covered by tall conifers and choked with ferns, phytosaurs lurked beneath the water and waited for prey.
"A phytosaur resembles a crocodile," Mueller said. "They had basically the same lifestyle as the modern crocodile by living in and around the water, eating fish, and whatever animals came to the margins of the rivers and lakes. But one of the big differences is the external nares, the nose, is back up next to its eyes instead of at the end of its snout."
Mueller said scientists can tell the sexes of the animals by a distinctive feature on males. A bony crest stretched from the nostrils by the eyes to the tip of the animal's beak -- a feature lady phytosaurs probably found sexy.
Judging by the female's skull size, which is more than three feet in length, Mueller guessed she would have measured 16 to 17 feet in length from nose to tail tip. The male would have measured about 17 to 18 feet. Their thin jaws suggested they hunted mainly fish as opposed to big prey.
Mueller said phytosaurs lived throughout the Triassic period from 230 to 203 million years ago, but died out during a mysterious mass extinction. Highly successful animals, they are commonly found because these animals liked to live in swampy areas and were more likely to become covered in sediment and fossilized.

Posted Image
The skull of the phytosaur Machaeroprosopus lottorum.

http://www.sciencedaily.com/releases/2014/01/140129145634.htm




Journal Reference:
Axel Hungerbühler, Bill Mueller, Sankar Chatterjee, Douglas P. Cunningham. Cranial anatomy of the Late Triassic phytosaur Machaeroprosopus, with the description of a new species from West Texas. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 2013; 103 (3-4): 269 DOI: 10.1017/S1755691013000364

ABSTRACT
The skull anatomy of a new species of the phytosaur Machaeroprosopus is described for the first time on the basis of two specimens from the Upper Triassic Cooper Canyon Formation of Texas. Additional information is provided by a third specimen referred to Machaeroprosopus sp. A paranasal bone, an additional paired element of the narial region, is identified. Important new data are presented for the braincase, including the morphology of the epipterygoid and presphenoid, an anterior process of the prootic, an anteroventral process of the laterosphenoid, and a parasphenoid process. Machaeroprosopus lottorum n. sp. is characterised by four apomorphies: a supratemporal fenestra closed on the skull roof with bevelled anterior rim, a comparatively short squamosal, a flat and rugose narial rim, and medially extended palatines that come close to form an ossified secondary palate. With respect to the supratemporal fenestra, the supraoccipital–parietal complex and several features of the squamosal, Machaeroprosopus lottorum n. sp. bridges the morphological gap between species previously referred to the genera Pseudopalatus and Redondasaurus. A parsimony analysis of known species of Machaeroprosopus supports the hypothesis that the development of the rostral crest in Machaeroprosopus is a sexually dimorphic feature, and questions the validity of the genus Redondasaurus. Consequently, Redondasaurus is here considered a junior synonym of Machaeroprosopus.

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9036378
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